Poster Authorship

For a local symposium, I am making a poster. This work stems from a lab mate's work, which showed an in vivo effect of treatment and has been published. My work is looking at the mechanism of this effect. I would like to show the figure from the in vivo paper in my background section to help explain the why of my work. Should this other person be included as an author for my poster, or is simply referencing his paper sufficient? Or should I not include this image, since technically it's not my work? Opinions please!

If they are still working on the project then authorship (and reference) would be appropriate, but if they are now working elsewhere just a reference would be suitable. It is unusual to reproduce published work on these sorts of things.